Telephony standards relating to non-landline operations such as, by way of example and not by way of limitation, cellular telephone operations and Voice over Internet Protocol (VoIP) operations, have mandated that an Automatic Location Identification database (ALI) shall maintain connectivity with a positioning center that is able to provide current location information for a non-landline call. Using currently extant technology, a positioning center provides a caller's location and callback number to the ALI, and the ALI passes that information to a requesting Public Safety Answering Point (PSAP; sometimes referred to as a Public Safety Answering Position). An ALI may maintain connectivity with more than one positioning center using various interface types, both standard and non-standard. By way of example and not by way of limitation, a positioning center may include (1) a Gateway Mobile Location Center (GMLC) that retrieves forwards, stores and controls emergency position data within a GSM (Group Speciale Mobile; or Global System for Mobile communications) location network; (2) a Mobile Position Center (MPC) that is a positioning center for retrieving, forwarding, storing and controlling emergency position data within an ANSI (American National Standards Institute) network; or (3) a Voice over Internet Protocol (VoIP) positioning center (VPC) that retrieves, forwards, stores and controls emergency position data with a VoIP network.
During the course of an emergency PSAP will try to determine location of the calling party so that decisions can be made regarding where to send aid or the like. In a landline call, obtaining an address may be carried out by simply consulting a local Automatic Numbering Identification (ANI) database or a local ALI database to obtain caller location information. In the case of an emergency service call placed by a mobile device such as, by way of example and not by way of limitation, a wireless mobile device or a VoIP device, it may be necessary that reliance be placed upon a Position Determining Entity (PDE).
Systems relying on a PDE for location information relating to a calling party employ a pseudo Automatic Number Identification (pANI) identifier to assure that the PDE will have a call back number for the requesting PSAP. A pANI may also be referred to as Emergency Service Routing Digits (ESRD). The terms refer to a number used in place of the mobile phone number of the caller that permits routing information to be sent to a wireline 9-1-1 system via an SS7 network. A pANI may be embodied in an Emergency Service Routing Key (ESRK) for use with wireless mobile emergency call networks. A pANI may be embodied in an Emergency Service Query Key (ESQK) for use with VoIP networks. An ESRK/ESQK is commonly a 10-digit routable—but not necessarily dialable—number that is used for routing as well as a correlator, or key, for mating data that is provided to a PSAP via different paths. By way of example and not by way of limitation, data may be provided to a PSAP via a voice path and via an ALI data path.
The emergency service keys ESRK/ESQK are commonly used to query an ALI database for location of a given emergency caller. An emergency service key ESRK/ESQK may be provided to a selective router associated with the PSAP and may operate as the calling number/ANI for calls to the PSAP associated with a PDE query. The emergency service key is used by a selective router as a key to selective routing data associated with an emergency call. The emergency service key is delivered by the selective router to an associated PSAP as the calling number/ANI for the emergency call and is used by the PSAP to request ALI information indicating location of the device making the emergency call (i.e., the emergency caller).
Solutions and systems commonly in place today establish a finite pool of emergency service keys ESRK/ESQK for allocation during operation. Generally, one ESRK/ESQK is issued and employed for each respective extant emergency call. When an emergency call is completed, the associated ESRK/ESQK is returned to the pool for later use. As may be appreciated by one skilled in the art of emergency communication network design, it is possible to exhaust the number of available ESRK/ESQKs if the number of extant emergency calls is too great, either because of a high number of calls, or because too many emergency service calls have too great a duration, or because of a combination of a high number of calls and longer duration calls. Some systems use timers to assure that an emergency service key ESRK/ESQK is available for reassignment. However, timers are necessarily based upon estimated call duration. Cutting an emergency call off after an arbitrary (estimated) time may cut off an emergency caller from urgently need assistance. Such a situation may have disastrous—even deadly—consequences, no matter how well-intentioned the estimate may have been. Consequences may be particularly disastrous if there is updated location information available after an emergency routing key ESRK/ESQK is returned to the pool.
Increasing the number of emergency service keys ESRK/ESQK in a pool is inefficient and may lead to number exhaustion for emergency service keys ESRK/ESQK system-wide.
There is a need for a method for determining termination of an emergency service call.
There is a need for a method for managing emergency service keys that substantially accounts for actual duration of emergency service calls.